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## Arguments

DL
(input) REAL or COMPLEX array, shape with .
The subdiagonal of .

D
(input) REAL or COMPLEX array, shape with .
The diagonal of .

DU
(input) REAL or COMPLEX array, shape with .
The superdiagonal of .

B
(input/output) REAL or COMPLEX array, shape with or shape with .
The matrix .

X
(output) REAL or COMPLEX array, shape with and , or shape with .
The solution matrix .

DLF
Optional (input or output) REAL or COMPLEX array, shape with size(DLF) .
If FACT = 'F' then is an input argument that contains the multipliers that define the matrix from the factorization of .
If FACT = 'N' then DLF is an output argument that contains the multipliers that define the matrix from the factorization of .

DF
Optional (input or output) REAL or COMPLEX array, shape with size(DF) .
If FACT = 'F' then DF is an input argument that contains the diagonal of the matrix .
If FACT = 'N' then DF is an output argument that contains the diagonal of the matrix .

DUF
Optional (input or output) REAL or COMPLEX array, shape with size(DUF) .
If FACT = 'F' then DUF is an input argument that contains the first superdiagonal of .
If FACT = 'N' then DUF is an output argument that contains the first superdiagonal of .

DU2
Optional (input or output) REAL or COMPLEX array, shape with .
If FACT = 'F', then DU2 is an input argument that contains the second superdiagonal of .
If FACT = 'N', then DU2 is an output argument that contains the second superdiagonal of .

IPIV
Optional (input or output) INTEGER array, shape with .
If FACT = 'F' then IPIV is an input argument that contains the pivot indices from the factorization of .
If FACT = 'N', then IPIV is an output argument that contains the pivot indices from the factorization of ; row i of the matrix was interchanged with row . will always be either or ; indicates a row interchange was not required.

FACT
Optional (input) CHARACTER(LEN=1).
Specifies whether the factored form of is supplied on entry. Default value: 'N'.

TRANS
Optional (input) CHARACTER(LEN=1).
Specifies the form of the system of equations: Default value: 'N'.

FERR
Optional (output) REAL array of shape , with , or REAL scalar.
The estimated forward error bound for each solution vector (the -th column of the solution matrix ). If is the true solution corresponding to , is an estimated upper bound for the magnitude of the largest element in divided by the magnitude of the largest element in . The estimate is as reliable as the estimate for RCOND and is almost always a slight overestimate of the true error.

BERR
Optional (output) REAL array of shape , with , or REAL scalar.
The componentwise relative backward error of each solution vector (i.e., the smallest relative change in any element of or that makes an exact solution).

RCOND
Optional (output) REAL.
The estimate of the reciprocal condition number of the matrix . If RCOND is less than the machine precision, the matrix is singular to working precision. This condition is indicated by a return code of .

INFO
Optional (output) INTEGER If INFO is not present and an error occurs, then the program is terminated with an error message.
References:  and [17,9,20,21].     Next: Example (from Program LA_GTSVX_EXAMPLE) Up: General Linear Systems Previous: Description   Contents   Index
Susan Blackford 2001-08-19